Aluminium oxide is impermeable and, unlike the oxide layers on many other metals, it adheres strongly to the parent metal. If damaged mechanically, aluminiumâs oxide layer repairs itself immediately.
Saliva helps remove oral waste and cavity-causing bacteria, protects teeth from decay by neutralizing harmful acids, and helps re-mineralize tooth enamel. Saliva also keeps oral tissues healthy by preventing infection by controlling bacteria and fungi in the mouth.
Salivary Glands. Salivary glands produce saliva, which moistens the mouth to help a person chew and swallow food. Saliva also contains substances (enzymes) that begin the breakdown of food. There are four pairs of salivary glands: 1  The parotid glands are located between the ear and the jaw.alivary Glands. Salivary glands produce saliva, which moistens the mouth to help a person chew and swallow food. Saliva also contains substances (enzymes) that begin the breakdown of food. There are four pairs of salivary glands: 1  The parotid glands are located between the ear and the jaw.